In recent years, progress in an electronics field has successively led to research and development of new electronics materials. A polymer compound having electrical conduction properties is also one of them, and draws attention as a new electrically conductive material in place of a conventional metallic material.
An electrically conductive material using a polymer has advantages of allowing production in a simpler technique and in a relatively less expensive manner in comparison with the metallic material, and is expected for practical use.
In a case of the metallic material, generally, a film of the metallic material is formed by adhering or depositing the material on a substrate by a vapor phase process such as a vacuum deposition process and a sputtering process, to produce the electrically conductive material. However, this method requires a large amount of cost for a production apparatus or the like, and is unsuitable for large scale production. Moreover, research has recently been conducted for shifting substrate materials from glass to a plastic in order to meet a desire for achieving light-weight or flexible electrical equipment. However, in view of heat resistance, glass is generally used for the substrate in the vapor phase process. Use of a plastic substrate has some problems such as insufficient heat resistance, a decrease in adhesion of a formed coating film to the substrate, resulting in being easily detached, or the like.
In contrast, an electrically conductive material using an electrically conductive polymer essentially requires neither a high temperature nor vacuum conditions, and therefore a production step therefor is simple, and thus production cost can be suppressed. A material such as the plastic can also be utilized as the substrate, and therefore can be achieved light-weight or flexible equipment, and also significantly improved strength and impact resistance of the equipment. Moreover, film formation can be made by a coating method such as spin coating, and therefore the electrically conductive material is also suitable for production of a large area film or the like.
In view of such advantages, it is suggested that the electrically conductive polymer is applied to various kinds of uses, such as a transparent electrode for a liquid crystal display or a solar cell, an electrode material for a condenser, a capacitor, or a secondary cell, an antistatic material, an organic semiconductor material used for an organic electroluminescence (organic EL) device or an organic transistor, and a material for electronic circuit patterning, and research for practical use has started.
Specific examples of the electrically conductive polymers that are currently used include a polymer compound having an electron conjugated system in a molecule, such as polyacethylene, poly-p-phenylene, polypyrrole, polyaniline, and polythiophene. In order to improve an electrical conductivity, doping of a carrier into these polymers is carried out, and as a dopant, a halogen atom, protonic acid, Lewis acid, a metal halide, or the like is known. Further, an improvement in suitability for various kinds of uses is also made by adding any other component to the electrically conductive polymer. For example, Patent literature 1 proposes an electrically conductive resin-formable composition in which a photocuring monomer and a curing accelerator are formulated with an electrically conductive polymer, and describes that the monomer is subjected to a curing reaction to allow an improvement in mechanical strength and adhesion to a substrate, and that selective light irradiation is applied to allow use as a pattern-forming material. Patent literature 2 proposes an electrically conductive coating composition in which a thermal crosslinking agent and a crosslinking accelerator are formulated with a composite formed of an electrically conductive polymer and a dopant, and describes that the composition has low-temperature curability to allow application to a substrate having low heat resistant, and that the composition can be used as an antistatic layer for a packaging material of an electronic component, or the like. Moreover, Patent literature 3 proposes a pattern-forming material in which an electrically conductive polymer is used as a matrix polymer, and an acid-degradable resin and a photoacid generator are formulated therewith.
Among these prior literatures, the electrically conductive material described in Patent literature 1 or 2 is proposed for the purpose of improving adhesion of a resin film to the substrate, heat resistance, or the like by the curing reaction of the resin. However, Patent literature 1 and 2 do not describe improvement of the electrical conductivity. Moreover, Patent literature 3 discloses the use of the photoacid generator for the purpose of forming a fine pattern on the polymer resin using a charged beam. However, Patent literature 3 does not aim at an improvement in the electrical conductivity by using the photoacid generator.